Chronic venous insufficiency of the lower extremities is a disorder which is widespread in the population. The cause thereof is frequently an impaired function of venous valves. Recent investigations demonstrate that the pathogenesis of varicose veins is causally connected to altered elastic properties within the vessel wall leading to dilatation of the vein wall. As a result of the dilatation, the venous valves are no longer able to close, leading to an increased reflux of blood into the affected veins and finally to the development of varicosis. In particular, non-closure of the terminal valve of the great saphenous vein (GSV) is frequently the starting point of primary varicosis.
The range of possible therapies for incompetence of the trunk of the great saphenous vein extends from conservative measures such as, for instance, compression stockings, physio- and pharmacotherapy, via minimally invasive procedures to surgical procedures. Conventional surgical treatment consists of removing (stripping) the incompetent veins. However, very recently, minimally invasive procedures such as, for example, endovascular laser therapy (ELT) and radiofrequency obliteration (RFO) have increasingly been used. One disadvantage of the surgical and minimally invasive procedures is, however, that the relevant veins are respectively removed from the body and obliterated in the body.
The general desire to retain venous bypass material for coronary bypass surgery, and the objective of minimizing surgical trauma have led to the development of various vein-retaining surgical procedures. Particular mention should be made in this connection of so-called “extraluminal valvuloplasty” of the GSV terminal valve. Function of the valve is restored in that method of treatment by placing a cuff around the dilated valve region. It is possible by that surgical technique to eliminate pathological refluxes into the veins of the lower extremities without removing the veins themselves. Examples of such cuffs are disclosed in WO 88/00454 A1, U.S. Pat. No. 5,147,389, U.S. Pat. No. 4,904,254 and WO 02/076305 A1. However, the disadvantages of the cuffs described therein are, besides the elaborate and therefore costly manner of their manufacture, especially the fact that the cuffs described therein consist of materials with low or zero extensibility, and thus the cuff does not have extensibility appropriate for the vein.
A comparatively simple vein cuff made of Dacron® (polyethylene terephthalate) has been successfully employed by Mumme et al. (Phlebologie 2004; 33: 149 to 155) for extraluminal venous valve reconstruction in clinical studies. However, a problem with this cuff material too is that it has little elastic extensibility. It is moreover generally known that the Dacron® may induce foreign-body reactions, especially fibrotic reactions (S. Raju, ANN. SURG. (1983) 197, 688 to 697).
It could therefore be helpful to provide a sheathing for varicose veins which overcomes the known problems. The sheathing is intended in particular to have elasticity appropriate for veins and be biocompatible and able to be manufactured easily and at low cost.